Fundamentals of General Chemistry, Exam #3 with Solutions

Exam #3 Name___________________________________ 1) Chlorine (atomic number = 17) has the electronic configuration: ________. A) 1s2 2s2 2p 6 2d 6 3s1 B) 1s2 2s2 2p 6 3s2 3d 5 C) 1s2 2s2 2p 6 2d 5 3s2 D) 1s2 2s2 2p 6 3s2 3p 5 E) 1s2 2s2 2d 103s2 2) The complete electron configuration of argon, element 18, is __________. A) 1s6 2s6 2p2 3s4 B) 1s4 2s4 2p10 C) 1s2 2s2 2p6 3s2 3p6 D) 1s2 2s2 2p103s2 3p2 E) 1s4 2s4 2p6 3s4 3) The condensed electron configuration of silicon, element 14, is __________. A) [Ne]2p10 B) [He]2s6 2p2 C) [He]2s4 D) [Ne]3s2 3p2 E) [He]2s4 2p6 4) Give the ground state electron configuration for Cd. A) [Kr]5s2 4d 10 B) [Kr]5s2 5d 10 C) [Kr]4d105s2 D) [Kr]5s2 4d 105p2 E) [Kr]4d10 5) Give the ground state electron configuration for Pb. A) [Xe]6s 2 5d 106p2 B) [Xe]4f145d 106p2 6s2 C) [Xe]6s 2 6p2 D) [Xe]6s 2 4f145d 106s2 6p2 E) [Xe]6s 2 5f146d 106p2 6) Choose the ground state electron configuration for Zn 2 ⁺. A) [Ar]4s2 3d 8 B) [Ar] C) [Ar]4s2 3d 6 D) [Ar]3d10 E) [Ar]3d8 1 7) How many unpaired electrons are present in the ground state Kr atom? A) 1 B) 5 C) 0 D) 3 E) 2 8) How many unpaired electrons are present in the ground state Ge atom? A) 3 B) 1 C) 2 D) 0 E) 4 9) Place the following elements in order of increasing atomic radius. P Ba Cl A) Ba < Cl < P B) Cl < P < Ba C) P < Cl < Ba D) Cl < Ba < P E) Ba < P < Cl 10) Place the following in order of decreasing radius. Te2 ⁻ F⁻ O2 ⁻ A) F⁻ > Te2 ⁻ > O2 ⁻ B) F⁻ > O2 ⁻ > Te2 ⁻ C) Te2 ⁻ > O2 ⁻ > F⁻ D) O2 ⁻ > F⁻ > Te2 ⁻ E) Te2 ⁻ > F⁻ > O2 ⁻ 11) Which reaction below represents the second electron affinity of S? A) S(g) → S⁺(g) + e⁻ B) S⁻(g) → S(g) + e⁻ C) S2 ⁻(g) → S⁻(g) + e⁻ D) S⁻(g) + e⁻ → S2 ⁻(g) E) S(g) + e⁻ → S⁻(g) 12) Which ionization process requires the most energy? A) O(g) → O+ (g) + e B) F+ (g) → F2+ (g) + e C) F(g) → F+ (g) + e D) O+ (g) → O2+ (g) + e - 2 13) Which of the following represent the Lewis structure for S2 ⁻? A) B) C) D) E) 14) Which of the following reactions is associated with the lattice energy of Li 2 O (ΔH°latt)? A) 2 Li⁺(aq) + O2 ⁻(aq) → Li2 O(s) B) 2 Li⁺(g) + O2 ⁻(g) → Li2 O(s) C) Li2 O(s) → 2 Li⁺(aq) + O2 ⁻(aq) D) 2 Li(s) + 1 O (g) → Li2 O(s) 2 2 E) Li2 O(s) → 2 Li⁺(g) + O2 ⁻(g) 15) Identify the compound with the highest magnitude of lattice energy. A) NaCl B) CsCl C) LiCl D) KCl 16) A double covalent bond contains __________ of electrons. A) 0 pairs B) 1 pair C) 4 pairs D) 2 pairs E) 3 pairs 17) Place the following elements in order of decreasing electronegativity. S Cl A) Cl > Se > S B) S > Cl > Se C) Se > S > Cl D) Cl > S > Se E) Se > Cl > S Se 18) Which molecule or compound below contains a pure covalent bond? A) PF3 B) Li2 CO 3 C) NaCl D) SCl6 E) Cl2 3 19) Choose the best Lewis structure for BeF2 . A) B) C) D) E) 20) Choose the best Lewis structure for OCl 2 . A) B) C) D) E) 21) Choose the best Lewis structure for ICl 5 . A) B) C) D) E) 4 22) Draw the Lewis structure for NO2 ⁻ including any valid resonance structures. Which of the following statements is TRUE? A) The nitrite ion contains two N=O double bonds. B) The nitrite ion contains two N-O bonds that are equivalent to 1 1 2 bonds. C) The nitrite ion contains one N-O single bond and one N=O double bond. D) The nitrite ion contains two N-O single bonds. E) None of the above are true. 23) How many of the following elements can form compounds with an expanded octet? Pb Kr Si B A) 1 B) 3 C) 4 D) 0 E) 2 24) Choose the bond below that is the strongest. A) N=O B) N-I C) N-S D) N=N E) N-O 25) Place the following in order of decreasing bond length. H-F H-I H-Br A) H-I > H-Br > H-F B) H-F > H-I > H-Br C) H-I > H-F > H-Br D) H-Br > H-F > H-I E) H-F > H-Br > H-I 26) Use the bond energies provided to estimate ΔH° rxn for the reaction below. Bond C-H C-O C=O O=O O-H CH3 OH(l) + 2 O 2 (g) → CO2 (g) + 2 H 2 O(g) Bond Energy (kJ/mol) 414 360 799 498 464 A) -91 kJ B) +473 kJ C) -486 kJ D) -392 kJ E) +206 kJ 5 ΔH°rxn = ? 27) Choose the INCORRECT statement. A) Pairs of electrons not involved in bonding are called lone pairs. B) In a Lewis structure, a covalent bond can be represented by a pair of electrons or a dash. C) Three electron pairs involved in a bond produce a triple bond. D) Two electrons involved in a bond produce a double bond. E) A molecule of two atoms is called a diatomic molecule. 28) Based on the Lewis structures, which of the following molecules would you expect to exhibit resonance? A) LiH B) HNO2 C) CH4 D) OF 2 E) none of these 29) Which of the following molecules is nonpolar? A) HCN B) HClO4 C) CHCl3 D) BCl3 E) H2 O 30) Which of the following molecules is polar? A) CS2 B) NH4 + C) PCl5 D) NBr3 E) CH4 31) What is the formal charge on N in NO 3 - ? A) 0 B) +2 C) +1 D) -1 E) -2 32) Which of the following resonance structures for OCN⁻ will contribute most to the correct structure of OCN⁻? A) O(1 lone pair)≡C-N(3 lone pairs) B) O(2 lone pairs)=C=N (2 lone pairs) C) O(1 lone pair)=C(2 lp)=N(1 lone pair) D) O(3 lone pairs)-C≡N(with 1 lone pair) E) They all contribute equally to the correct structure of OCN⁻. 33) Give the approximate bond angle for a molecule with a trigonal planar shape. A) 105° B) 109.5° C) 90° D) 180° E) 120° 6 34) Determine the electron geometry (eg) and molecular geometry (mg) of BrF 3 . A) eg=trigonal bipyramidal, mg=see-saw B) eg=tetrahedral, mg=trigonal pyramidal C) eg=trigonal bipyramidal, mg= T-shape D) eg=trigonal planar, mg=trigonal planar E) eg=trigonal planar, mg=bent 35) Determine the electron geometry (eg) and molecular geometry (mg) of XeF 2 . A) eg=trigonal bipyramidal, mg=bent B) eg=linear, mg=linear C) eg=tetrahedral, mg=linear D) eg=tetrahedral, mg=bent E) eg=trigonal bipyramidal, mg=linear 36) Consider the molecule below. Determine the molecular geometry at each of the 3 labeled atoms. A) 1=tetrahedral, 2=tetrahedral, 3=trigonal planar B) 1=trigonal planar, 2=tetrahedral, 3=trigonal pyramidal C) 1=tetrahedral, 2=tetrahedral, 3=tetrahedral D) 1=trigonal planar, 2=tetrahedral, 3=tetrahedral E) 1=trigonal planar, 2=trigonal pyramidal, 3=trigonal pyramidal 37) Determine the electron geometry (eg), molecular geometry (mg), and polarity of SO 2 . A) eg=tetrahedral, mg=tetrahedral, nonpolar B) eg=trigonal planar, mg=bent, polar C) eg=tetrahedral, mg=bent, polar D) eg=linear, mg=linear, nonpolar E) eg=trigonal pyramidal, mg=trigonal pyramidal, polar 38) Describe a pi bond. A) p orbital overlapping with a d orbital B) side by side overlap of p orbitals C) overlap of two s orbitals D) end to end overlap of p orbitals E) s orbital overlapping with the end of a p orbital 39) Identify the number of electron groups around a molecule with sp hybridization. A) 5 B) 1 C) 3 D) 2 E) 4 7 40) A molecule containing a central atom with sp 3 d hybridization has a(n) __________ electron geometry. A) octahedral B) tetrahedral C) trigonal planar D) trigonal bipyramidal E) linear 41) Draw the Lewis structure for SO3 . What is the hybridization on the S atom? A) sp3 d2 B) sp3 d C) sp3 D) sp2 E) sp 42) Draw the Lewis structure for BrF5 . What is the hybridization on the Br atom? A) sp2 B) sp3 d2 C) sp3 d D) sp3 E) sp 43) Consider the molecule below. Determine the hybridization at each of the 3 labeled atoms. A) 1=sp, 2=sp2 , 3=sp2 B) 1=sp2 , 2=sp3 , 3=sp3 C) 1=sp2 , 2=sp3 , 3=sp2 D) 1=sp3 , 2=sp3 , 3=sp2 E) 1=sp3 , 2=sp3 , 3=sp3 44) Draw the Lewis structure for the molecule CH 2 CHCH3 . How many sigma and pi bonds does it contain? A) 9 sigma, 0 pi B) 8 sigma, 2 pi C) 9 sigma, 1 pi D) 7 sigma, 2 pi E) 8 sigma, 1 pi 8 45) What volume of a 0.716 M KBr solution is needed to provide 30.5 g of KBr? A) 21.8 mL B) 42.7 mL C) 357 mL D) 184 mL 46) A solution is prepared by dissolving 16.2 g of benzene (C6 H6 ) in 282 g of carbon tetrachloride (CCl4 ). The concentration of benzene in this solution is __________ molal. The molar masses of C6 H6 and CCl4 are 78.1 g/mol and 154 g/mol, respectively. A) 0.736 B) 0.0543 C) 0.102 D) 7.36 × 10-4 E) 5.43 47) How much water must be added to 40.0 g of CaCl2 to produce a solution that is 35.0 wt% CaCl 2 ? A) 87.5 g B) 54.0 g C) 114 g D) 74.2 g 48) At 20°C, a 0.376 M aqueous solution of ammonium chloride has a density of 1.0045 g/mL. What is the mass % of ammonium chloride in the solution? The formula weight of NH4 Cl is 53.50 g/mol. A) 0.381 B) 2.00 C) 0.374 D) 2.68 E) 0.705 49) Identify the colligative property. A) boiling point elevation B) osmotic pressure C) freezing point depression D) vapor pressure lowering E) all of the above 50) Calculate the molality of a solution formed by dissolving 27.8 g of LiI in 500.0 mL of water. A) 0.241 m B) 0.394 m C) 0.254 m D) 0.415 m E) 0.556 m 51) Determine the vapor pressure of a solution at 55°C that contains 34.2 g NaCl in 375 mL of water. The vapor pressure of pure water at 55°C is 118.1 torr. A) 87.1 torr B) 112 torr C) 108 torr D) 115 torr E) 92.8 torr 9 52) Determine the freezing point of a solution that contains 78.8 g of naphthalene (C 10H8 , molar mass = 128.16 g/mol) dissolved in 722 mL of benzene (d = 0.877 g/mL). Pure benzene has a melting point of 5.50°C and a freezing point depression constant of 4.90°C/m. A) 0.74°C B) 1.33°C C) 4.17°C D) 1.68°C E) 4.76°C 53) Place the following solutions in order of increasing osmotic pressure. I. 0.15 M C2 H6 O2 II. 0.15 M MgCl 2 III. 0.15 M NaCl A) II < I < III B) III < I < II C) I < II < III D) I < III < II E) II < III < I 54) Identify the solute with the highest vanʹt Hoff factor. A) MgCl 2 B) MgSO4 C) NaCl D) nonelectrolyte E) FeCl 3 55) Choose the aqueous solution that has the highest boiling point. These are all solutions of nonvolatile solutes and you should assume ideal vanʹt Hoff factors where applicable. A) 0.100 m NaCl B) 0.100 m C6 H12O6 C) 0.100 m AlCl3 D) 0.100 m MgCl 2 E) They all have the same boiling point. 10 Answer Key 1) D Page Ref: Reference: Section 8-11 2) C Page Ref: 8.4 Reference: 3) D Page Ref: 8.4 Reference: 4) C Page Ref: 8.4 Reference: 5) B Page Ref: 8.4 Reference: 6) D Page Ref: 8.7 Reference: 7) C Page Ref: 8.4 Reference: 8) C Page Ref: 8.4 Reference: 9) B Page Ref: 8.6 Reference: 10) C Page Ref: 8.7 Reference: 11) D Page Ref: 8.8 Reference: 12) B Page Ref: 8.7 Reference: 13) C Page Ref: 9.4 Reference: 14) B Page Ref: 9.4 Reference: 15) C Page Ref: 9.4 Reference: 16) D Page Ref: 9.5 Reference: 11 17) D Page Ref: 9.6 Reference: 18) E Page Ref: 9.6 Reference: 19) E Page Ref: 9.7 Reference: 20) C Page Ref: 9.7 Reference: 21) A Page Ref: 9.7 Reference: 22) B Page Ref: 9.8 Reference: 23) B Page Ref: 9.9 Reference: 24) A Page Ref: 9.10 Reference: 25) A Page Ref: 9.10 Reference: 26) D Page Ref: 9.10 Reference: 27) D Page Ref: Reference: Section 10-2 28) B Page Ref: Reference: Section 10-5 29) D Page Ref: Reference: Section 10-7 30) D Page Ref: Reference: Section 10-7 31) C Page Ref: Reference: Section 10-4 32) D Page Ref: 9.8 Reference: 12 33) E Page Ref: 10.2 Reference: 34) C Page Ref: 10.4 Reference: 35) E Page Ref: 10.4 Reference: 36) B Page Ref: 10.4 Reference: 37) B Page Ref: 10.5 Reference: 38) B Page Ref: 10.7 Reference: 39) D Page Ref: 10.7 Reference: 40) D Page Ref: 10.7 Reference: 41) D Page Ref: 10.7 Reference: 42) B Page Ref: 10.7 Reference: 43) B Page Ref: 10.7 Reference: 44) E Page Ref: 10.7 Reference: 45) C Page Ref: 12.5 Reference: 46) A Page Ref: 12.5 Reference: 47) D Page Ref: 12.5 Reference: 48) B Page Ref: 12.5 Reference: 13 49) E Page Ref: 12.5 Reference: 50) D Page Ref: 12.5 Reference: 51) D Page Ref: 12.6 Reference: 52) A Page Ref: 12.6 Reference: 53) D Page Ref: 12.6 Reference: 54) E Page Ref: 12.6 Reference: 55) C Page Ref: 12.7 Reference: 14